In today's lesson, you will learn what Linux is, where Linux came from, what a Linux distribution is and some of the reasons that Linux is favorite for certain applications and projects over other operating systems. First and foremost, Linux is an operating system. An operating system is simply a collection of software that manages hardware resources and provides an environment where applications can run. The operating system allows applications to store information, send documents to printers, interact with users and other things. Linux is also a Kernel. Typically when the term Linux is used it refers to the Linux operating system as a whole. However, it can refer to just the Linux Kernel as well. The Linux Kernel is the core or the heart of the operating system. It's the layer that sits between the hardware and applications. Said another way it's the intermediary between software and hardware. However, to have a useful operating system you need other components in addition to the Kernel. These components can include system libraries, graphical user interfaces, Email utilities, web browsers and other programs. Linus Torvalds created Linux when he was a student at the University of Helsinki studying computer science. In early 1991, he purchased an I.B.M compatible personal computer that came with the MS-DOS operating system. Linus wasn't satisfied with MS-DOS and wanted to use a Unix operating system like he was accustomed to at the university. When he set out to obtain a copy of Unix for his personal use, he found that the least expensive Unix he could buy was about 5,000 U.S dollars. Driven by the desire to run a Unix like operating system on his personal computer, he set out to create Linux. Linus and over 100 developers worked on Linux over the next couple of years and in March of 1994, version 1.0 of the Linux Kernel was released. Linux is open source software. This means that anyone can use, copy, study and change the software in any way they choose so long as the source code is openly shared with others. To date, thousands of people have made improvements to Linux. And with Linux being free and open source software, it has led to the rise of Linux distributions. In every case, the source code is free, but in some cases the distribution is not free. The binaries, the compile code is not free. For example, you have to pay a license in order to run Red Hat Enterprise Linux. However, Red Hat releases their source code for anyone to download. Again, Linux is not a Unix derivative. It was written from scratch. However, many of the commands that are found in Linux are also found on Unix. If you have any experience on a Unix system, you're going to feel right at home on a Linux system. A Linux distribution is the Linux Kernel and a collection of software that together create an operating system. Each distribution has its own goals and areas of focus. Your choice of distribution will depend on what you are trying to accomplish. There are distributions that are commercial. These commercial Linux distributions are backed by corporations and you can buy support from them. There are noncommercial Linux distributions. These are maintained by a community volunteers. You have Linux distributions that are designed for server use, others that are designed for desktop use, some that are focused on research and science. There are others that are focused on multimedia production. There are literally hundreds of Linux distributions. DistroWatch.com is a great website to learn about all the available Linux distributions. Distro is short for distribution. On your screen I've listed some popular Linux distributions, Red Hat Enterprise Linux, Fedora, Ubuntu, Debian, SuSE Linux Enterprise Server, OpenSuSE, Linux Mint. Again, there are hundreds of these. These are just a few of the most popular Linux distributions. To get an idea of exactly what's available, go to DistroWatch.com. So what are some of the reasons you would want to run Linux? Linux runs on many hardware platforms, from dedicated networking devices to phones to personal computers and even super computers. Proprietary Unix operating systems typically only run on their hardware from their company. For example, HP-UX only runs on HP servers. AIX only runs on I.B.M servers. Linux can run on HP, I.B.M and other servers. Linux was developed on P.C hardware using Intel processors. Over time Linux has been ported to more hardware platforms than any other operating system. The small footprint of Linux allows it to run on older hardware or on embedded systems. Also, Linux is known for being stable, reliable, and secure. This makes it a great choice for servers that need to continuously run without downtime. Linux is traditionally been used for server applications. Linux can be used to host websites, act as file servers and even run database software. Linux doesn't have to be used as a server though. I find Linux to be a good everyday operating system that I use on my personal desktop. As a matter of fact, I'm recording this course with software that is running on Linux. Linux is free. Not only is the source code freely available, but you can run Linux on your hardware without having to pay a licensing fee in many cases. However, if your business depends on servers that are running Linux, having a commercial Linux distribution, which you pay for and having someone that can provide support can be well worth your while. Linux is typically not as costly as the proprietary Unix operating systems. Linux is also free in the sense that you can use it for any purpose and you can modify it to fit your needs if you so desire. There are also many free software applications that run on Linux. Many of these free applications were written specifically with Linux in mind. Let's recap what we've gone over in this lesson. First, we learned that Linux is an operating system. When someone says the word Linux without a qualifier, more than likely they are talking about the entire operating system. However, Linux is also a Kernel. When people speak of the Linux Kernel they are typically specific and say the Linux Kernel. Linux being the operating system is the intermediary between hardware and software. Linux distributions are implementations of Linux. Each Linux distribution has a different goal and a slightly different focus. Your choice of distribution will be driven by the goal you are trying to accomplish.